With eight-channel Kirkpatrick-Baez (KB) X-ray microscope applied to China's Shenguang-Ⅲ (SG-Ⅲ) laser facility, the effect of aiming error on imaging performance and the consistency of multichannel KB microscope were analyzed. The spatial resolution, image interval and system efficiency of X-ray microscope were simulated by ray-tracing model as a function of the field of view (FOV), object distance and image distance, respectively. The spatial resolution decreased by about 2.9 μm within range of ±200 μm and the efficiency of microscope system declined by about 60% within range of ±150 μm. The change of image interval and the efficiency of the microscope system were 0.67 mm and 7% respectively, when variety of object distance was changed within ±200 μm. The change of image interval was about 0.70 mm, when the image distance varies within range of ±20 mm. The results indicated that the aiming error of central FOV had a great effect on spatial resolution and system efficiency but it had no significant effect on image interval. The aiming error of object distance has impact upon image interval while it has lower influence on spatial resolution and system efficiency.